This invention relates to surgical methods and apparatus in general, and more particularly to methods and apparatus for making an ACL repair.
A ligament is a piece of fibrous tissue which connects one bone to another.
Ligaments are frequently damaged (e.g., detached or torn or ruptured, etc.) as the result of injury and/or accident. A damaged ligament can impede proper motion of a joint and cause pain.
Various procedures have been developed to repair or replace a damaged ligament. The specific procedures used depend on the particular ligament which is to be restored and the nature and extent of the damage.
One ligament which is frequently damaged as the result of injury and/or accident is the anterior cruciate ligament (ACL). Looking now at FIG. 1, an ACL 5 is shown extending between the top of the tibia 10 and the bottom of the femur 15. A damaged ACL 5 can cause instability of the knee joint, further damage to other structures, and cause substantial pain and arthritis.
Numerous procedures have been developed to restore a damaged ACL through a graft ligament replacement. In general, these ACL replacement procedures involve drilling a bone tunnel 20 (FIG. 2) through tibia 10 and up into femur 15. Then a graft ligament 25, consisting of a harvested or artificial ligament or tendon, is passed through tibial tunnel 30, across the interior of the joint, and up into the femoral tunnel 35. Then a distal portion of graft ligament 25 is secured in femoral tunnel 35 and a proximal portion of graft ligament 25 is secured in tibial tunnel 30.
There are currently a variety of ways to secure graft ligament 25 in a bone tunnel. One way is to use an interference screw 40 (FIG. 3), such as the ARTHREX interference screw, to xe2x80x9cdirectlyxe2x80x9d wedge graft ligament 25 against the side wall of bone tunnel 20. Another way is to use a bearing structure and expansion screw 45 (FIG. 4), such as the INNOVASIVE INTRAFIX system, to xe2x80x9cindirectlyxe2x80x9d wedge graft ligament 25 against the side wall of the bone tunnel 20. Still another way is to use a fastener device 50 (FIG. 5), such as the INNOVASIVE LYNX system, to secure graft ligament 25 in bone tunnel 20. Yet another way is to use an anchor 55 (FIG. 6), such as the MITEK ligament anchor, to suspend graft ligament 25 within bone tunnel 20. And another way is to use a suture suspension system 60 (FIG. 7), such as the ACUFEX ENDOBUTTON system, to suspend graft ligament 25 in bone tunnel 20. And still another way is to use a cross-pinning system 65 (FIG. 8), such as the ARTHREX cross-pinning system, to suspend graft ligament 25 in bone tunnel 20. And yet another way is to pass graft ligament 25 completely through bone tunnel 20 and affix graft ligament 25 to the outside of the bone with a screw and washer arrangement 70 (FIG. 9) or a staple (not shown).
Some of the aforementioned reconstruction techniques utilize a graft ligament which is harvested so as to include a portion of bone block, e.g., a patellar tendon including a portion of the patella. Others of the aforementioned reconstruction techniques utilize a graft ligament which is harvested so as to consist entirely of soft tissue, e.g., a harvested hamstring tendon.
In general, it is preferable to harvest graft ligaments consisting entirely of soft tissue, e.g., a hamstring tendon, since this involves less trauma to the donor site. However, graft ligaments consisting entirely of soft tissue are more difficult to biologically integrate into the host bone, due to the fact that two different types of tissue are involved, i.e., both tendon and bone. Such difficulties with biological integration can raise questions as to the adequacy and permanence of the ligament reconstruction. As a result, many ligament reconstructions are still effected using a graft ligament which includes a portion of bone block. While such xe2x80x9cbone blockxe2x80x9d reconstructions generally result in more significant trauma to the donor site, they also simplify biological integration of the graft ligament into the host bone since, within a bone tunnel, bone heals to bone more readily than tendon heals to bone.
In addition to the foregoing, ligament reconstructions tend to be complex surgical procedures where a variety of factors must be carefully balanced in order to achieve the best possible results. More particularly, in order to optimize the ligament reconstruction and minimize trauma to the surrounding anatomy, it is generally necessary to position a sizable graft ligament at exactly the right location within the joint, taking care to minimize trauma to the host bones by making the smallest possible bone tunnels. More particularly, when creating the ligament reconstruction, it is generally important to use as much graft ligament material as possible, so as to (i) provide the highest possible graft strength along the length of the graft, whereby to prevent subsequent rupture, and (ii) provide an extensive supply of collagen material, whereby to facilitate effective integration of the graft ligament into the bone. At the same time, the physics of the knee joint dictate the location of the graft ligament and hence the location of the bone tunnels, and the particulars of the surrounding anatomy may effect graft ligament size and/or bone tunnel size. And in addition to the foregoing, it is also generally important to minimize the size of the bone tunnels. Minimizing the size of the bone tunnels is important, since (i) larger bone tunnels are more destructive of the host bone, (ii) larger bone tunnels are more difficult to revise later on in the event of graft failure, and (iii) larger bone tunnels have larger diameters and, since bony ingrowth commences from the periphery of the bone tunnel, may reduce the proportion of tendon experiencing bony ingrowth, thereby weakening graft fixation. Thus it will be seen that the relative sizing of the graft ligament and the bone tunnels is a delicate balance involving a range of factors.
In addition to all of the foregoing, there must also be sufficient clearance between the graft ligament and the walls of the bone tunnels to permit the graft ligament to be pushed and/or pulled into position within the bone tunnels. And to further complicate the matter, in many cases, the surgeon must also be able to position surgical instruments within the bone tunnels, alongside the/graft ligament. Thus, xe2x80x9creal estatexe2x80x9d becomes a very precious commodity in ligament reconstructions. In practice, in order to permit deployment of the graft ligament within the bone tunnel, the graft ligament must generally be sized so as to have a cross-sectional area at least somewhat less, and in some cases significantly less, than the cross-sectional area of the bone tunnels it is to be deployed in.
Unfortunately, there are at least three significant problems associated with xe2x80x9cundersizingxe2x80x9d the graft ligament relative to the bone tunnel. First, such undersizing tends to undermine biological integration of the graft ligament with the host bone. Second, it can allow some movement of the graft ligament to occur relative to the host bone. Such movement can further impede the aforementioned biological integration; in addition, it can also result in abrasion, and hence deterioration, of the graft ligament and/or the host bone. Third, undersizing of the graft ligament relative to the host bone tunnel can also permit the incursion of synovial fluid into the bone tunnel. Such synovial fluid incursion is believed to result in degradation of the bone tunnel and/or in degradation of the biological integration of the graft ligament into the host bone.
As a result, one object of the present invention is to provide an improved way of effecting a ligament reconstruction using graft ligaments consisting entirely of soft tissue, yet which facilitates effective biological integration of the graft ligament with the host bone.
Another object of the present invention is to provide a way to temporarily reduce the size of the graft ligament so as to facilitate easy deployment of the graft ligament in the bone tunnels, while still permitting the graft ligament to return to its normal size so as to be sized more closely to the size of the bone tunnel and thereby eliminate the xe2x80x9cundersizingxe2x80x9d problems referred to above.
These and other objects are addressed by the provision and use of the present invention, which comprises a new procedure for graft ligament reconstruction. The procedure involves the following steps (i) harvesting a graft ligament consisting entirely of soft tissue, e.g., a hamstring tendon; (ii) compacting the tendon through compression, so as to significantly reduce its cross-sectional area and increase the density of its collagen material; and (iii) deploying the compressed tendon in the body, using the reconstruction technique of choice. Compacting can be effected using a variety of instruments, e.g., squeezing pliers, hinged plates, a conical tube, etc.